Conventionally, seats for, e.g., cars have a synthetic resin board member placed on the back side of a seat back so as to form the back surface of the seat back (see, e.g., Patent Literature 1). When a backseat occupant or passenger presses the seat back of a seat in front of him/her, this board member serves not to allow the influence of such pressing to be transmitted to the back of a passenger or occupant seated on this seat.